Use IPCC Files with iOS Devices by Enabling Carrier Testing Mode in iTunes

iTunes carrier testing mode allows you to manually load signed .ipcc carrier files onto an iPhone or cellular iPad, these .ipcc files contain various carrier settings pertaining to voice mail, MMS and SMS, Personal Hotspot, APN settings, and other network-specific preferences. If you've used an iPhone on T-Mobile or even as a prepaid phone you may have experience with these files, but other than making network configuration easy they can also be used to forcibly enable features that are otherwise disabled by default, like Personal Hotspot on certain international iPad 4G devices. We'll cover how to enable carrier testing mode, how to find ipcc files, and then how to use those IPCC files with either an iPhone or iPad with a cellular connection.

Enabling Carrier Testing Mode in iTunes

The process to enable carrier testing is a bit different for Mac OS X and Windows.

Mac OS X:

1. Quit out of iTunes
2. Launch Terminal from /Applications/Utilities/
3. Enter the following command at the prompt and then hit return:

   defaults write com.apple.iTunes carrier-testing -bool YES

4. Relaunch iTunes

Windows:
If you happen to use an iOS device with Windows, iTunes carrier testing mode is enabled by launching iTunes as an exe with a flag attached to it:

%ProgramFiles%\iTunes\iTunes.exe" /setPrefInt carrier-testing 1

Finding & Downloading .ipcc Files
All signed ipcc carrier settings files are stored in an xml file on apple.com, you can access that gigantic list here:

http://iphonediags.apple.com/version.xml

Find the carrier file you want to use and then copy the URL and paste it into your browser address bar to download it directly from Apple. Save that file somewhere that it is easy to find for using with iTunes.

Loading .ipcc Files onto an iPad or iPhone with iTunes

Now that carrier mode is enabled, you can load carrier files onto the iOS device. In either OS X or Windows:

1. Connect the iOS device to the computer
2. Launch iTunes and hold the Option key while clicking on "Check for Update" to load an .ipcc file
3. Select the .ipcc file to sync the .ipcc to the iOS device
4. Disconnect the iOS device and reboot it for changes to take effect

We were sent this tip as a method to forcibly enable the Personal Hotspot wi-fi router on Australian 3rd gen iPads, which apparently ship with the feature disabled by default. The solution to that problem is apparently just a matter of loading an ipcc file and rebooting the iPad. Thanks to Jeremy for the tip info!